This invention relates to a method of providing a display for a graphical user interface (GUI) and to a computer program, a computer-readable storage medium and apparatus for the same. In particular, the invention relates to providing a display for a graphical user interface in which a user may define a selected region of a subject image displayed in the display.
The requirement to select a region of a given subject image in a display is well known and arises in many applications. One such example is in the field of radiology in which a radiographer may be required to focus in on or select diagnostically relevant image parts within an overall radiographic image. In this field, the requirement to be able to select an area of interest quickly and accurately is particularly important because of the scarcity of the skilled human resource, i.e. the radiographer""s time. Four methods of achieving this are described at line 31 of column 8 to line 8 of column 9 of EP-A1-0523771.
The first method described requires a user to draw a contour by moving a light mark in the display under visual control, say using a co-ordinate pen or mouse, and the selected region of interest is defined as all image points contained in the contour. In the second method, the region of interest is defined as all the image points enveloped by a rectangle, itself defined by the user selecting upper left and bottom right corners. Similarly, in the third and fourth methods described, the regions of interest are defined as all the image points enveloped by a circle defined by its centre and a radial point, and a polygon defined by its corners respectively.
It is further known to manipulate the profile of a region already selected. One such method of manipulation is illustrated in FIG. 1 in which a display 1 is shown having a window 2 which frames a subject image 3. The selected region is rectangular, say selected using the second method described in EP-A1-0523771, and denoted by markers 5, four positioned at each corner and four at the midpoint of each side. The markers may be moved using a drag-and-drop technique and the shape of the selected region manipulated accordingly. This method is well known and implemented in commercial image processing packages such as Microsoft(trademark) Photo Editor 3.0.
However, in the field of radiography and indeed many other fields with GUI applications requiring quick and accurate part image selection, there is a continual need to increase productivity and one way this may be achieved is to provide an enhanced selecting method. It is therefore an object of the invention to provide a method for providing a display for a graphical user interface in which a user may select a region of a subject image more quickly and efficiently.
According to the present invention, a method comprises the steps of displaying the subject image; displaying at least one mask over the subject image wherein at least part of the or each mask extends to the periphery of the subject image; and defining the selected region as those parts of the subject image not covered by a mask, preferably where the outer periphery of at least one mask defines at least part of the profile of the selected region, wherein the or each mask has a geometry which may vary in accordance with a user""s input whereby the user selecting a first point within a mask and a second point displaced therefrom causes the geometry of that mask to vary in relation to the displacement between the first and second points.
Such a method provides a quick and efficient method of selection and especially where the function to move a mask is not pre-selected but initiated upon selection of the first point within the mask. Also, with at least part of the or each mask having a variable geometry and extending to the periphery of the subject image, they may be xe2x80x9cstoredxe2x80x9d at the periphery of the subject image thereby not interfering with viewing the subject image when not in use.
In addition, manipulating a selected region may be achieved by selecting a point anywhere within a corresponding mask, thereby accommodating a degree of inaccuracy with respect to point selection. Conversely, in the conventional arrangement shown in FIG. 1, discrete points defining the profile of the selected region have to be selected. Of course, it is known to highlight an enlarged area immediately adjacent to such discrete points as shown by feature 5 of FIG. 1, and thereby enable selection of a discrete point by selection of a point anywhere within the enlarged area. As such, it will be understood that the present invention is not intended to cover this arrangement.
In order to further simplify selection, when a user selects a first point within overlapping masks and a second point displaced therefrom, the geometry of the overlapping masks may be made to vary simultaneously, thereby reducing the number of instructions for varying the geometry of overlapping masks as would be needed if they were varied individually.
Given that subject images are typically rectangular, it is convenient that the or each mask may be is associated with a single side of the subject image whereby the geometry of the or each mask may only vary in a direction perpendicular to its associated side of the subject image. In such an arrangement, it is preferable that four masks are displayed, each associated with different sides of the subject image.
Conveniently, the first and second points are selected using a drag and drop technique thereby enabling the geometry of a mask to be varied in one single movement, for example, by one stroke of a screen pen on a touch sensitive screen or by one mouse movement.
Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying figures in which: